My understanding is that rooting an android smartphone or tablet allows you to add functionality and to flash custom ROMS (amongst other things) like MIUI or CyanogenMOD.
A Nexus device offers the pure "vanilla" android experience from Google without the additional "skins" etc. that mobile phone companies add/tweak to further differentiate their product from one another.
If it is the case that nothing has been added/tweaked, customised etc. on a Nexus 4/7/10, can I achieve this personalisation (via the Google Play Store) on such a device without the need for rooting?